advice for drilling for 3-inch waste

It didn't take me long to discover that I like self-feeding bits for drilling through studs and plates for my vent and drain lines. I have a medium duty 1/2" Dewalt right angle drill (DW120K, I couldn't justify buying a Hawg).

What advice can you all offer me for drilling the hole to accomodate the 3-inch ABS (main drain and vent) that I am putting into my remodel? Hole saws seem to be too shallow to go through double plates...what does anybody recomend?

Also, I'm using a 2 9/16ths for the 2-inch ABS and a 2 1/8th for the 1.5"

3" and 4" Schedule 40 pipe ODs are 3.500 and 4.500 respectively. Add at least 1/16" for the hole saw.

You may have trouble holding the drill for a self feeding bit in the size you are looking at for 3 and 4" pipe.

The solution for the double plates is usually to clear the hole saw after each plate. If the wood gets stuck and stays in the hole instead of coming out with the hole saw, you may need to apply a chisel or put a screw in the piece to pull it out.

I have found that a Roto-Zip with a 1/4" straight carbide bit does a great job where you may not have exactly the right size, or where you may not have clearance for drill access. Just handle it like a big Dremel tool, but with both hands. And hang on tight. I had one come out of my hands once and it fell and tore my pants where it came within a couple of inches of affecting my social life.

Go with the sawzall. You are going to have to use a nail plate either way. No one will see it after the wall goes up. For your vent roof penetrations, go with the hole saw. As suggested, if using the hole saw through plates, clear as you go. If you are doing work in old walls and encounter true 2x4s, the hole saw will not even go through one plate.

If you want to use a hole saw, Jad's method is best to get throught he thicker framing members. However, that leaves you no wiggle room. If you just cut through the plates, you can add an inch or so to the diameter and give yourself a little margin for error. Simpson makes some straps that will serve as protection from nails and to tie the framing together. Youa re not the first carpenter to fear plumbers and their sawzalls and hole saws. It can get ugly.

I just went through the same thing with my remodel. You can get 3 5/8" or 3 9/16" self feed bits on ****, but even there they go for $60-$80, so I gave up waiting for a good buy. I ended up with a Blu-Mol 4" hole saw from Home Depot for $17 ( I already had the arbor). I really like the Blu-Mol because they cut 1 7/8" deep and can easily go through 2" lumber.